Rocker support for building structures and the like



' July 23, 1940. F. N. ROPP 2,208,872

ROCKER SUPPORT FOR BUILDING SIRUCTURES AND THE LIKE A rro R/ws'ys.

F. N. ROPP July 23, 1940.

2,208 ROCKER SUPPORT FOR BUILDING STRUCTURES AND THE LIKE Filed Feb. ll,1958 2 Sheets-Sheet 2 Twzz y A TroR/vms.

Patented July 23, 1940 geen RocKER SUPPORT FoR BUTLDING STRUCTURES ANDTHE LIKE Franklin N. Ropp, Los Angeles, Calif., assigner to Soule SteelCompany, Los Angeles, Calif.

Application February 11, 1938, Serial No. 189,989

8 Claims.

` My invention relates to supporting means for buildings and otherstructures, with special ref,- erence to the type of support thatpermits relative lateral movementbetween a structure and the earth.

Damage to a building structure by earthquake maybe broadly attributed tothe fact that the relatively high inertia of a building structureprevents the structure as a Whole from freely following the relativelysharp and irresistible lateral movements of the earth. It is well knownthat the damage may be largely averted by providing freedom forlateralrelative movement between the building structure and the earth,and various means for the floating support of structures have l beenproposed for such purpose.

"Some of the prior art devices in this field have the disadvantage ofbeing excessively complicated in structure; some are relatively costlyto manufacture; and other prior art devices require excessive spaceallowance vertically or horizontally. For example, some of the prior artarrangements require relatively large pits or extensive basements tohouse elaborate cradles or similar understructures. The general objectof my invention is to provide, in contrast with these prior art devices,a floating support means that is siml ple, relatively inexpensive, andthat requires4 a minimlum of space.

Some prior inventors have sought the required mobility by insertingsupporting balls between alstructure and its base, and providing someexpedient to maintain a normal central disposition of the building onthe supporting balls. Ball arrangements may, in general, be lesscomplicated,

less expensive, and less subject to structural failure than cradlesuspensions, but the designer of a ball-bearing building support isconfronted with a certain dilemma. If he decides to employ relativelysmall balls, a large number will be required for even an averagebuilding. The resistance involved in relative movement between abuilding and the earth represents the unabsorbed force of an earthquakemovement that is transmitted to the building; for this reason it is notdesirable to raise friction to excessive values `by the employmient ofnumerous small balls. If, on the other hand, fewer relatively largeballs are decided upon by a designer to reduce` frictiorLthe cost perball mounts rapidly and the problem of providing space for ball movementmay become formidable. l

An object of my invention is to avoid this dilemma in a constructionwithout sacrlcing the rolling contact characteristic of `aball-bearingarrangement. More specifically, it is my purpose to provide in abuilding support, rolling contact surfaces having relatively large radiiof curvature without employing balls of corresponding radii, and withoutthe necessity of providing the'space either vertically or horizontallyrequired by such balls.

In each of the various ball arrangements old in the art, some equalizingmeans is required to keep the mobile building normally in a centralizedposition. For example, opposing springs have beenl used in somearrangements, and in others concave surfaces have beenprovided tocooperate with the balls. In my invention, by contrast, I propose toprovide the equivalent of such equalizing means in the congurationsupport members themselves.

Broadly described, the supportY which I achieve the above objects and inwhich I embody the equalizing functionconstitutesa rocker having aconvex supporting surface shaped to permit rolling movementin anylateral direc'-` tion and to provide a certain eccentricity that, causesthe superimposed structureto seek its nor-,

mal disposition at all times.

The above and further objects of my invention will be apparent in mydetailed description to follow, Yconsidered with the accompanyingdrawings. H l

In the drawings: Fig. 1 is a diagrammatic representation of thepreferred formUof-my rocker` showing the relationship involved.

Fig. 2 is a similar diagrammatic representa-l tion of a second form ofmy rocker.

Fig. 3 is a vertical section through a typical building showing` a basestructure xedly related to the earth and a superstructure iioatinglyFig. 7 isa viewsimilar to Fig. to show that the rocker member ofthesupport unit may be employed in reverse disposition.

Fig. 8 is a` View similar to Fig. 4 showing one of my support unitsmounted on top o'fasecond support unitl to indicateu how a building mayinof the variousY `member by corporate a plurality of such unitsarranged in tiers.

For the purpose of disclosing the relationships involved in thefunctioning of my invention, I show in Fig. 1 a structural member I0resting upon a rocker member II, the rocker member in turn resting on abase member I2. The lower end. I3 of the rocker is spherical inconfiguration and rests in a socket III concentric therewith. Since therocker member oscillates about a fixed point C1 at the center ofcurvature of the socket M, the rocker may be regarded as pivotallyrelated to the base member I2, and the lower end of the rocker may betermed the pivot end. The upper end of the rocker is convex, preferablyspherical, to provide an arcuate surface I5 for rolling contact with thebearing face I6 of the structural member I0. For economy of material,the body of the rocker may be formed with a lower cylindrical portion II from which wings I8 extendy radially to brace an arcuate end wall I9providing the rolling surface I5.

Any relative lateral movement between the structural member I and thebase member I2 will result in oscillation of the rocker about the pointC1. The radius of such oscillation is defined as the shortest distancebetween C1 and the convex rolling surface I5. This radius R1 in the formof my invention shown in Fig. 1 may also be regarded as the effectivelength of the rocker, but in other forms of my invention, as will appearhereinafter, the radius R1 may not so aptly be termed the length of therocker.

Fig. l shows a second radius R2 measured from the rolling face I to thecenter of curvature C2 of that face. At the heart of my invention is theconception that a certain useful eccentricity may be provided by simplydesigning the rocker with R2 greater than R1.

'I'he character and effect of the eccentricity involved may beunderstood by reference to Fig. 1 in which the rocker is tilted to showthe eifect of a sudden shift of the earth, displacing the bottom of therocker laterally a distance S. It will be noted that the upper bearingpoint B follows the center of curvature C2, being always directly abovethat center. But the center of curvature C2 because of the tilt of vtherocker, is displaced laterally a distance e in addition to the displacenment S of the center of oscillation C1, the result being that thebearing point B is shifted laterally a greater distance than the bearingmem-A ber I2. The additional shift of the bearing point B produces amoment tending to restore vertical alignment between the bearing point Band the point C1 through which the vertical resistance supporting theload of vthe structural member IIJ is exerted. In addition to thismoment, there is also a gravitational tendency of the rocker to returnto its normal vertical disposition, since any oscillation of the rockerfrom that normal disposition elevates the structural member I0.

If friction is neglected, the resistance to clisplacement of the rockerfrom its normal vertical position is equal to the tendency of the rockerto return to that position, and both depend upon the relative lengths ofR1 and R2, both increasing with increase in the relative difference. Anyfriction involved in the oscillation of the rocker, however, increasesthe resistance of the rocker to movement away vfrom its normal verticaldisposition, but decreases the tendency of the rocker to return to itsnormal disposition from a displaced position.

Part of the friction is in the rolling resistance of the sphericalsurface I5 in contact with the bearing face l' and the remainder of thefriction is caused by sliding contact of the lower spherical end I3 inthe socket I4. The rolling resistance can be reduced only by decreasingthe permissible bearing value on Contact surfaces, which reduction isaccomplished by increasing the radius of curvature of the arcuatesurface I5. The socket resistance to oscillation of the rocker may bereduced by decreasing the radius of curvature of the socket or byincreasing the length of the rock* er, and, regardless of dimension, maybe minimized by proper lubrication.

Knowing that the degree of responsiveness of the rocker to lateralforces depends upon the eccentricity involved or the relative lengths ofthe two radii R1 and R2, together with the mentioned factors offriction, those skilled in the art may readily design rockers for specicrequirements. A too sensitive arrangement will permit a building torespond undesirably to ordinary wind pressures, but, on the other hand,since the total resistance attributable to eccentricity and frictiondetermines the proportion of shock transmitted to the building structureduring an earthquake, it is desirable that such total resistance he notgreater than necesary to allow for wind pressures.

The required radius of the convex rolling surface I5 of the rocker is afunction of a constant times 1/EX1oad divided by the permitted bearingvalue on the contact surface. Thus, if a load N of 150,000 lbs. isassumed, the permissible steel stress 5m being 20,000 lbs. per sq. in.and E the coefficient of elasticity being 30,000,000, then the radius ofcurvature for the convex surface The diameter d of the shaft to providesuch contact may be ascertained from the formula =7.5 sq. in.

from which it is found that d=i% in., say lil/2v in.

The frictional resistance at the socket is the load times the frictionalcoeiiicient times the radius of the rocker shaft, divided by the lengthof the rocker. Taking the frictional coefficient as .2 and assuming theshaft to be 33 in. long, the horizontal force to overcome the socketfriction:

The rolling resistance of the convex face of the rocker N 1W 5m-E(l-F)=2580 lbs.

The total force required to overcome friction then is 2050+2580=4630lbs., and the coeiicient against lateral movement:

.ZX X2.25=2050 lbs.

X sin aeoa'sve velopedby thefmovemen't of a rocker constructed inaccordance withhthe `above calculations will Ibe The rise of the loadcaused the structure will `be 9-5/e2-1.2s52,=.09 inch The forces tending`toreturn the load to normal disposition of therocker creates a moment,the value of which is l by the oscillation of (1,285+ 442%)150,000='195,500 meh-pounds The starting moment required to overcome thefrictional resistance=33 4630==1153,000 inchpounds. The returningcmomentthenis inexcess of` the starting moment by 42,500inchpounds,`representing aforceof The rocker needfnot be designed forball-andmay be regarded as oscillating `abouta centerk C1 that shiftsboth laterally ancllvertically`and R1, the radius of 1 oscillation ofthe rocker, may be` taken as the shortest measurement from `C1 to eitherof the two faces 32 and 33. Theeccentricity developed by` this form ofmy rocker depends upon the length of R1 relative to both Rz the radiusof curvature ofthe face 32, and R3 the radius of curvature of the face33, eccentricity being developed by both of the spherical facesof' therocker.

i The manner in which my rocker may be incorporated in a building isindicated by the remaining figures of the drawings. All of these figuresincorporate the rst form of my rocker shown in Flgnl, but it will beapparent that 'other forms of the rocker, such as shown in Fig.` 2 forexample, may be employed in the same manner with equal facility. Y l

In Fig. 3, I show a multi-story superstructure, designated by thenumeral 35, fioatingly supported `on a base structure generallydesignated by the numeral 36. Since allowance must be made for relativelateral movement between the superstructure and the base structure, Iprefer to arrange the plurality ofsupporting rockers Il on a level at orabove the ground level 38. In such an arrangement the exterior columns39 of the base structure may lie against the earth 40 with nointervening clearance for relative movement. As shown` in the drawings,both the exterior columns 39 and the interior columns 42 of the basestructure are supported by buried foundation structure43, and thevarious base columns are interconnected by stay struts 44 shown in theform of I-beams. It is apparent that the whole base structure is rigidlyrelated to the earth.

As best shown in Figs. 4, 5, and 6, a rocker unit, Y

generally designated by the numeral 45, comprises a base member 46 and astructural member 41 floatingly supported by the rocker ll'seated in thebase member. The base member 46 is incorporated in the construction of abasement column 42 to comprise an integral part of the base structure 36shown in Fig. 3. Preferably the base members 46 will be distributed onthe level by the I-beam stay struts 44.v In the preferred form of myinvention, the base member has the general conguration of a pan, and,therefore, may be employed to retain a suitable quantity of lubricant 48to minimize friction in the socket I4. The floating structural member 41is incorporated in a column 49 of the superstructure that corresponds tothe basement column associated with the base member 46.

Just above the rocker unit 45 may be the rst floor 50 of the buildingsupported by floor beams 52 interconnecting the various columns 49 ofthe superstructure. Above the first oor 50 of the superstructure areadditional floors, the second iloor 53 supported by beams 54 and thethird floor 55 supported by beams 56 being shown in the drawings. Sincethe points of supporter the aforementioned bearing points B of Fig. l,shift laterally under each column 49, when there is any relativedisplacement of the building, it is advisable to make the portions ofthe columns 49 between the rst floor 50 and the second floor 53 somewhatheavier than the portions above the second floor of the superstructure',as indicated in Fig. 3.

It will be noted that the floating structural member 41 in the preferredform of my invention has the form of an inverted pan so that the basemember 46 and the floating member 41 together form a housing normallyencasing the rocker member Il, the rocker being `completely enclosedexcept for a slight clearance 51 be-` tween the base member 46 and thefloating member 41. i l

Relative movement between the superstructure and the Abase structurecauses the rocker member to oscillate to a tilted position, as indicatedin Fig, 5, the base member 46 being displaced laterally with respect tothe floating member 41.

Preferably the rocker unit will 1be so ,designed` `of the base member 46may incline outward to present-a relatively extensive horizontal surface59 upon which the lower edge of the floating member 41 may come to restwhenever the rocker is tilted beyond an angle that will permit therocker to return to` normal. Such an arrangement prevents the buildingfrom being dropped any material distance if an earthquake should throwthe rockers out of operation.

Fig. '7 is similar to Figs. 4, 5, and 6, the essential 'difference beingthat the rocker memberl Il is shown in inverted position to indicatethat the rocker may be reversed without interfering with the functionsheretofore described. In this gure, the rocker unit of Figs. 4, 5, and 6is simply reversed, the base member 62 of Fig. 7 having theconfiguration of the iloating structural member 41 of Fig. 4 and theoating structural member63 of Fig. 7 having the configuration of thebase member 46 of Fig. 4.

'I'he purpose of Fig. 8 is to indicate that more than one level or tierof rocker units may 'be incorporated in a building structure withcertain advantages. The resistance to lateral movement of thelowerrocker unit. is transmitted fr tov the upper rocker unit, insteadiof,directly to the super-structure, with the result that shocks areabsorbed to an increased degree.

In Fig. S the base member 64 of the lower rocker unit 65 is incorporatedin the base structure. of the building in the same manner as the basemember 46 of Figs. 4 to 6. The base member 56 of the upper rocker unit.El rests upon the floating member 68 of the lower rocker unit 65. Thefloating member Eig of the upper rocker unit 6l is incorporated in thecolumn i9 of the superstructure in the same manner as the oatingstructural member 41 of Figs.v 4 to 6. While Fig. 8 shows the two levelsof rocker units as close together as possible, the two levels may beconsiderably spaced if desired.

For the purpose of disclosure and to illustrate the principles involvedin my invention', I have described specific forms of my rockerI and:rocker unit in explicit detail. It will be apparent to those skilled inthe art, however,that the forms shown and described may be variouslychanged modified without. departing fromA the spirit of my conception. Ispecifically reservethe right to all such changes and modifications thatproperly come within the scope of my appended claims. i

I wish to point out4 also that my yinvention is not restricted tobuildingr structures nor is its function limitedy to the cushioning ofvearthquake shocks. Itv will be readily recognized by those skilled inwidely divergent arts that the principles of my conception areapplicable to any arrangement where it is desirable to support anelement in a laterally yieldable manner with an inherent tendency tomaintaina centralized normal position. For example, it is conceivablethat a loading platform subject to occasional lateral impact might be somounted as to yield to such impact with minimum damage. It is to benoted that such a platform would serve as a bumper to decelerate withoutdamage a vehicle making the impact. This observation suggests theemploymentof my invention primarilyforsuch deceleration purpose.

A spherical rolling surface is employed in the particular form of myinvention set forth in this disclosure. A spherical rolling surface `isrequired, however, only in installations where the y displacement mayoccur inl diverse lateral directiene. In installations Where relativemovement is to be expectedl inonlyone direction, a cylindrical rollingsurface may besubfstituted.

I claim as myv invention:

l. In a building structure, the vcombination of:

a fixed base member; a structure member spaced above said base member,one of said members having a substantially plane supporting face; and arocker member iloatingly supporting said structure member on said basemember, said rocker memberhaving a convex surface in rolling Contactwith said plane supporting face, the radius of curvature of said convexsurface being greater than the radius of rotation of the rocker.

3. A rocker for floatingly supporting building structures and the likecomprising, an .elongated body portion providing a point at one endthereof and having a transversely extending wall with a convex outersurface at the opposite end thereof, the radius of curvature of saidconvex surface being of greater length than said elongated body portion.

4. A rocker for oatingly supporting building structures and the likecomprising, an elongated body portion providing a pivot at one endthereof ythan said elongated body portion.

5. A rocker for noatinglyv supporting building structures and the likecomprising, an elongated body portion providing a pivot at one endthereof and having a transversely.extendingvvall'with an Varcuate outersurface at lthe opposite end thereof, the radius of curvature of ,saidarcuate surface being of greater length than said elongated bodyportion. 6. A rocker for iloatingly supporting building structures andthe likecomprising, an elongated body portion rounded at `one endthereof and having a transversely extending Wall with an outer arcuatesurface at the opposite end thereof, and webs extending from saidelongated body portion reinforcing said Wall, the radius of curvature ofsaid arcuate surface being ofl greater length than said elongated bodyportion.

7. In a building structure', the combination of:

a base member fixedly related to thev earth;` a

building member; and a rockers'upporting the building member above thebase member, said rocker compriisng a'body having one end thereofrotatably engaging one of said members, and the other end of said bodyhaving an arcuate outer surface in rolling contact with the other ofsaid members, the radius of curvature of said arcuate surface being ofgreater length than said body. whereby when said rocker is oscillatedfrom its normal vertical position said building member will be slightlyraised by said arcuate surface thus creating a poential force forreturning said rocker toits original vertical position.

8. A rocker for the floating support of building structures and thelike, said rocker having a substantially spherical end for rollingcontact with a support surface, said spherical end having a radius ofcurvature greater than the vertical dimension of the rocker.

FRANKLIN N. ROPP.

